1. Field of the Invention
This invention relates to pressurized water reactors and, more particularly, to a modular former for use in the inner barrel assembly of such reactors.
2. State of the Prior Art
Baffle type structures have been known for use in the portion of a reactor which surrounds the reactor core, usually termed the lower barrel assembly. Such baffle structures typically are comprised of plates which are bolted together to form a unitary baffle structure. Since not positioned in the core outlet flow, such known baffle structures are not subjected to the same type of thermal transients and flow loads as can exist within the inner barrel assembly of a reactor, and particularly a reactor of the advanced design to which the present invention primarily is directed. Specifically, in a reactor of the type with which the modular former of the present invention is employed, the reactor internals of the inner barrel assembly includes several hundred rods, or rodlets, which are selectively movable in an axial, vertically oriented direction, into and out of the lower barrel assembly, to control the activity of the reactor core. The rodlets thus are positioned directly in the core outlet flow, rendering it critical to maintain substantially uniform distribution of the outlet flow from the reactor core in an axial direction as the flow passes along the rodlets and through the upper barrel assembly. The core outlet flow, moreover, at least potentially presents significant thermal stresses due to the core outlet flow transients and induces vibrations. Since these conditions and corresponding flow control requirements do not exist in conventional reactors, no corresponding structures are known in the prior art for performing the functions of the modular formers of the present invention.